Kaolin refractory and process of making the same



Patented Mar. 17, 1925 UNITED STATES 1,530,260 PATENT'OFFICE.

ISAAC HARTER, or Do-NGAN HrLLs, NE YORK, AND ANTHONY M. KOHLER, F

- JERSEY CITY, NEW JERSEY. e

KAOLIN REFRACTORY AND PROCESS OF MAKING SAME.

No Drawing.

To all whom it may concern:

- Be it known that we, ISAAC HARTER and ANTHONY M. KoHLnR, United States, and residents of Dongan Hills, in the county of Richmond and State of New .York, and of Jersey City,'in the county of Hudson and State of New Jersey, respectively, have invented certain new and useful Improvements in Kaolin Refractories and Processes of Making the Same, of

which the following is a specification.

Our invention relates to refractory products adapted foruse under high temperature furnace conditions and to processes for producing the same. More specifically our invention relates to refractories made'of kaolin.

It is known'that refractory materials requiring bond for molding or shaping, such as bauxite, chrome, magnesite, etc., have been seriously decreased in heat resistance by the presence of a bond having a lower softening point than fluxing action upon such materials. In such cases, the heat resistance of the block is at a point somewhere midway between these points or tempera tures. This is likewise true of kaolin.

' By our improved process, we are able to produce a refractory product, the heat resistance of which is not lowered by the influence of the binder.

We have also found that a-highly desirable refractory may be produced if the kaolin is melted, so as to permit the physiochemical changes to take place in the material withthe minimum resistance to such changes. When the refractory is made, we find that the shrinkage of the resulting product is substantially eliminated and that such refractory is capable of sustaining heavy loads under high temperature conditions and that the tendency of the refractory to spall when subject to sudden temperature changes is very greatly decreased.

The melting of the material, however, introduces many technical difliculties and we have found that substantially the same result's may be obtained if, instead of raising the temperature of the material to itsmelting.point, we raise such material to a. temperature just short of its melting point.

The following illustrative example discitizens of the Application filed May 25, 1923. Serial No. 641,520.

' closes our invention in the form at present preferred by us, but it will be understood that various modifications and changes may be made therein without departing from the spirit of our invention and without exceeding the scope of our claims.

We form crushed raw kaolin into blocks or biscuit of convenient size and dry and burn the blocks in a suitable kiln or furnace at a. temperature suflicient to cause the blocks to vitrify, so-that, when cool, the material is extremely hard and dense. This temperature may be varied, but we prefer to employ a temperature of at least 90% of the melting point temperature of the kaolin, whereupon itwill have undergone substantially maximum shrinkage. When burned at this temperature, the blocks become distorted, the kaolin material becoming extremely hard and filled with cleavage planes along which they are easily parted. Inasmuch as the bestresults will be obtained when highly refractory kaolin is used, this temperature may range from '2900 to 3250 F. vOrdinarily, the kaolin used by us will have a melting point within the softening points of Seger cones 32 and. 35 corresponding to temperatures of 3218 and 3326 F. respectively. See-Ries, Clays,

2d ed. pp. 182-183, .New York. 1908 for a standard table of Seger' cone softening as points; t

To facilitate handling of the raw biscuit, a small quantity of a temporary binder such as glucose or molasses may be used, which will burn out when the biscuit are fired. The blocks or biscuit are allowed to cool and are crushed to form a grog of a size which will vary according to the purpose for which it is to be used.

The product so made consists of clinkered particles which are dense and hard, are of irregular shape and are adapted to serve as the base for various refractory products, including cements, etc.

For the manufacture of fire-brick and 1 other refractories, the base material may be .bonded in the usual way but we prefer to proceed in a novel mannef as follows;

Ground biscuit or grog, made as above, is intimatel mixed with crushed, finely ground kao in, referably in the proportions of about t ree parts of the grog to one of the ground raw material, a. wet pan being convenient although any suitable apparatus may be used for this mixing. Preferably the ground kaolin will have substantially the same melting point as the kaolin used in forming the biscuit. In other words, the same raw kaolin will be used both for the grog and bond. Preferably the particles of grog will be about 3 mesh and fines and the crushed kaolin will be about mesh and fines. The mixture, to which water has been added to give proper consistency, is now molded, tempered, and, if necessary repressed and dried, these steps being amiliar to those skilled in the art.

The articles so formed are now burned in a suitable kiln or furnace at a temperature suflicient to produce an article having the desired hardness and structure, depending upon the use to which the finished article is to be put. In the case of fire-brick,

v we prefer to employ a temperature of from 3000 to 3250 Ft, depending upon the refractoriness of the kaolin used, although good results may be obtained using a considerably lower temperature.

The temperatures referred to throughout the specification were obtained using optic al pyrometers which were in agreement with the standard Seger cone-temperature. scale as above referred to.

B the methods of procedure above set fortii, we are able to produce refractory articles of requisite cohesion and rigidity from highly refractory material. Furthermore, the refractory qualities of these articles have in no way been influenced by the presence of any binding material.

Refractory articles made in accordance with our invention are characterized by a high resistance to sudden temperature changes or, in other words, have little tendenc to spall. In addition, they. are capa le of withstanding high load pressures under high temperature conditions.

While we have described the invention throughout the specification and claims with respect to kaolin, it will be understood that the use of other clays which may closely a proach or equal kaolin in refractory qua ities, for example flint clay, plastic clay, etc. is within the purview thereof.

We claim: 1. A refractory article consisting ofparticles of kaolin burned at a temperature of not less than 3000 F and bonded with kaolin.

2. A refractory article consisting of particles of kaolin burned at a temperature of not less than 3000 F. and mixed with kaolin to form a bond and burned at a temperature of not less than 3000 F.

3. A'refractor article consisting of particles of a dense urned kaolin bonded with kaolin in the proportion of approximately three parts of burned kaolinto one part of kaolin bond.

4. A refractory article consisting of particles of kaolin burned at a temperature of not less than 3000 F. and bondedwith kaolin, in the proportion of approximately three parts of burned kaolin to one part of kaolin bond.

. 5. A refractory article consisting of particles of kaolin burned at a temperature of not less than 3000 F. and mixed with kaolin to form a bond and burned at a temperature of not less than 3000 F., the proportion of burned kaolin particles to the kaolin bond being approximately three parts to one.

A 6. The process of making a refractory I article which consists .in mixing particles 'of clinkered kaolin with ground unburned kaolin and burning the mixture at a temperature sufiicient to cause the ound kaolin to bond the clinkered .partic es. I

' 7'. The process of making a refractory article which consists in mixing particles of clinkered kaolin with ground unburned kaolin in the proportion of approximately three parts'to one and burning the mixture at a temperature sufficient to cause the ground kaolin to bond the clinkered particles.

8. The process of making a refractory article which consists in mixing particles of clinkered kaolin with ground unburned kaolin and burning the mixture at a temperature of at least 90% of the melting .point temperature of the kaolin.

9. The process of makin a refractory article which consists in mixing particles of clinkered kaolin with ground unburned kaolin and burning the .mixture at a temperature of at least 3000 F.

ISAAC HARTER; A. M. KOHLER. 

